Bone densitometry, also called dual-energy x-ray absorptiometry or DEXA, uses a very small dose of ionizing radiation to produce pictures of the inside of the body (usually the lower spine and hips) to measure bone loss.It is commonly used to diagnose osteoporosis, to assess an individual's risk for developing osteoporotic fractures. DEXA is simple, quick and noninvasive. It's also the commonly used and the most standard method for diagnosing osteoporosis. A DEXA scan involves a much smaller radiationexposure than a standard chest X-ray.